Your typical screen today is wider than most content on the web needs it to be, so most web pages render as tall columns with ample margins. Vertical tabs use u

Your typical screen today is wider than most content on the web needs it to be, so most web pages render as tall columns with ample margins. Vertical tabs use up that space efficiently to show a large number of tabs in a way that makes it much easier to see all your tabs at a glance without losing track because the titles are shortened into nothing.